This invention relates to scanning sensors for determining attitude information for an orbiting body, and more particularly, to a yaw sensing conical scanner which can be used and combined with a conical sensor for providing three axes attitude information using a single horizon sensor head.
Horizon sensors are devices mounted on an orbiting body such as satellites, missiles, space probes, extremely high flying aircraft and the like which sense the horizon of a reference body and produce a signal which indicates orientation of the orbiting body with respect to the reference body. The attitude of the orbiting body which generally orbits the earth and is determined by its position with respect to three axes at right angles to each other, two of which are in a plane at right angles to a projected radius of the earth passing through the orbiting body which plane is parallel to the earth's horizon. Conical scan horizon sensors are frequently used in space craft to determine pitch and roll attitude by sensing the position of the earth's horizon in several directions. The third axis called yaw is the attitude around an axis through the center of the earth which cannot be obtained from horizon data and observations of some other celestial object or body, usually the sun are required. The problem in providing the various attitude information including yaw normally requires extra equipment or different sensor heads which are both costly, require increased power and add weight, all of which are undesirable.